Virus Linked to Prostate Cancer

Sept. 8, 2009 -- A virus may be responsible for some prostate cancers and
hold clues to the cause of the deadly disease, according to a new study.

Xenotropic murine leukemia virus-related virus (XMRV) has been previously
linked to leukemia and sarcomas in animals, but researchers say this has more
recently been identified in human prostate cancer samples.

"We found that XMRV was present in 27% of prostate cancers we examined and
that it was associated with more aggressive tumors," researcher Ila R. Singh,
MD, PhD, associate professor of pathology at the University of Utah, says in a
news release.

If further studies confirm that the virus causes prostate cancer,
researchers say it would open new avenues for diagnostic tests, vaccines, and
therapies for treating prostate cancer.

Prostate cancer affects one in six American men and is the most common type
of cancer among men after skin cancer.

Clues to Prostate Cancer's Cause

Previous studies have shown that a small group of men with a certain genetic
variation were more susceptible to infection with XMRV, and the virus was
present in about 10% of prostate cancer samples.

In this study, published in the Proceedings of the National Academy of
Sciences, researchers examined about 200 cancerous prostate samples as well
as 100 non-cancerous prostate samples.

They found 27% of the prostate cancers contained either XMRV DNA or proteins
compared to 6% of healthy prostate cells. The virus was also more likely to be
found in more aggressive prostate cancers.

In addition, the presence of XMRV was found in malignant prostate cancer
cells, a finding that indicates the virus may be directly related to the
formation of prostate cancer tumors or possibly that the virus has a preference
to replicate within prostate cancer cells.

Finally, researchers say infection with XMRV was seen regardless of whether
the men had the genetic variation making them susceptible to it, which would
expand the "at-risk" population from a small group of genetically predisposed
men to all men.

XMRV is a retrovirus that is known to cause cancer in animals but has not
been proven to cause cancer in humans. However, researchers say these results
show the virus merits further investigation as a potential cause of prostate
cancer.